In the case of an engine using gasoline, ethanol, and the like, as fuel, one of the most important factors for improving performance and fuel economy and decreasing exhaust gas is to improve combustion characteristics. A combustion process of a general spark ignition engine is a diffusion flame type process in which flame is expanded from an ignition source when the fuel is mixed with air and the fuel-air mixture is ignited by spark plug as illustrated in the following drawings.
In order to improve combustion characteristics in premixed combustion, the particle size of the fuel should be small and the fuel should be easily vaporized and easily mixed with air. To this end, technologies for improving spray characteristics of the injector and flow characteristics in the combustion chamber have been actively developed and applied. Combustion characteristics at a low temperature generally deteriorate due to deterioration of vaporization characteristic of the fuel. Therefore, in order to improve start-up performance at the time of cold start, the amount of the fuel is increased, power generation of an alternator is prohibited, and multi-ignition, or the like, is applied, thereby improving start-up performance.
Therefore, in order to improve the combustion characteristics at a low temperature, there is a need to improve start-up performance by optimizing heating control in the system to which a heated injector for increasing the temperature of the fuel is applied.